docs: def _create_structure_array(structure_array, voxelspacing):
      """
      Convenient function to take a structure array (single number valid for all dimensions
      or a sequence with a distinct number for each dimension) assumed to be in mm and
      returns a structure array (a sequence) adapted to the image space using the supplied
      voxel spacing.
      """
      try:
          structure_array = [s / float(vs) for s, vs in zip(structure_array, voxelspacing)]
      except TypeError:
          structure_array = [structure_array / float(vs) for vs in voxelspacing]
      
      return structure_array